The present invention relates to a motorcycle including a diagnostic system, and particularly a motorcycle including a diagnostic system that analyzes an ion signal for determining whether combustion occurred and for determining whether the spark generating circuit has an intermittent connection.
Ideally, combustion in an engine""s combustion chamber propagates from the spark plug through the combustible mixture along a controlled combustion wave. Knock occurs when the combination of the local pressure and heat within the combustion chamber is above the requisite local pressure and heat required for spontaneous combustion. This results in spontaneous combustion or auto-ignition being ahead of the combustion wave.
It is known to control knock in a four-cylinder, water-cooled automobile engine. One method entails obtaining an ion signal representing ionization across the spark gap of a spark plug. After obtaining the ion signal, a controller detects whether knock is present within the combustion chamber. If the controller detects knock, then the controller will vary the timing of the spark event. However, prior art two-cylinder, air-cooled motorcycle engines did not control knock within the engine, and were forced to accept the resulting loss of power. Prior art motorcycles did not have the necessary control and processing power required to implement knock control.
One of the characteristics of a two-cylinder, air-cooled engine (e.g., a two-cylinder, air-cooled motorcycle engine) is that the engine runs much hotter than a water-cooled engine (e.g., a water-cooled automobile engine). The most obvious reason for this is that water-cooled engines use a coolant for promoting heat removal, whereas air-cooled engines rely substantially on air-flow for heat removal. This problem is intensified if the motorcycle is running in warm surroundings. The increased running temperature of the motorcycle engine and increased temperature of the intake air results in an increased temperature within the combustion chamber and, consequently, the motorcycle engine is more susceptible to knock.
A second problem that arises with two-cylinder, air-cooled motorcycle engines is that air-cooled engines have a larger engine temperature range than water-cooled engines. That is, because air-cooled engines do not contain a liquid coolant, the engine temperature varies over a larger temperature range than water-cooled engines. Even further, a large number of motorcycle engines cannot be calibrated for spark timing at the peak power or peak. These motorcycle engines are calibrated at peak pressure because that is the point where the most amount of output power for the engine can be achieved without knock damage. Depending on how conservative the calibration is at elevated temperatures, knock can be an issue.
Knock is even more prevalent in two-cylinder, V-twin, air-cooled motorcycle engines having one cylinder positioned in front of the other. In such an engine, the rear cylinder typically runs hotter than the front cylinder because the rear cylinder receives less airflow then the front cylinder. The increased temperature for the rear cylinder results in the rear cylinder being more susceptible to knock than the front cylinder. Therefore, it would be beneficial to create a controller for performing knock control in a two-cylinder air-cooled motorcycle engine, and particularly in a two-cylinder, V-twin, air-cooled motorcycle engine.
The invention provides a motorcycle including a frame, front and rear wheels coupled to the frame for rotation with respect to the frame, and a two-cylinder engine mounted to the frame. The engine includes a housing, a crankshaft mounted for rotation within the housing, first and second cylinders having first and second combustion chambers, respectively, and first and second pistons reciprocating in the first and second cylinders, respectively. The engine of the motorcycle is preferably a two-cylinder, V-twin, air-cooled engine having one cylinder positioned in front of the other. The motorcycle further includes a spark generating circuit including a spark plug having a spark gap exposed to the first combustion chamber. The spark generating circuit produces a spark across the spark gap in response to a spark-inducing signal. The motorcycle further includes an ion signal circuit that provides an ion signal indicative of an ion current being generated across the spark gap. The motorcycle further includes an analysis module electrically connected to the ion signal circuit and the spark generating circuit. The analysis module generates the spark-inducing signal in a timed sequence, receives the ion signal from the ion signal generating circuit, measures a knock intensity within the ion signal, and modifies the timing sequence in response to an indication of knock in the first cylinder.
The motorcycle may further include a fuel injector having a fuel injector circuit. The fuel injector provides an amount of fuel to the combustion chamber in response to a fuel injector signal being provided to the fuel injector circuit. The fuel injector circuit is electrically connected to the analysis module. The analysis module generates the fuel injector signal and modifies the fuel injector signal in response to an indication of knock within the first cylinder.
The motorcycle may further include a second spark generating circuit substantially identical to the first spark generating circuit and a second ion signal circuit for use with the second cylinder. The analysis module is electrically connected to the second ion signal circuit and the second spark generating circuit and functions as described above to modify the second timing sequence. The provision of a second circuit facilitates separate control of the first and second cylinders.
In a second embodiment, the invention provides a motorcycle including a spark generating circuit having a spark plug. The spark plug includes a spark gap exposed to the first combustion chamber. The spark generating circuit produces a spark across the spark gap in response to a spark-inducing signal. The motorcycle further includes an ion signal circuit that generates an ion signal indicative of an ion current being generated across the spark gap. The motorcycle further includes a conditioning chip that receives the ion signal and generates a knock intensity signal. The motorcycle further includes a processor and software for operating the processor to provide a spark-inducing signal at a timed sequence, to determine whether the knock intensity signal represents knock within the first cylinder, and to modify the timed sequence in response to an indication of knock in the first cylinder.
The invention further provides a method of varying a spark event in a two-cylinder engine of a motorcycle. The method includes the acts of providing a motorcycle, generating a first spark in a first combustion chamber of the motorcycle with the first spark plug when the first piston is in a first position, obtaining an ion signal indicative of an ion current across the first spark plug gap, determining if the ion signal indicates knock within the first cylinder, and generating a second spark in the first combustion chamber with the first spark plug when the piston is in a second position and in response to an indication of knock in the first cylinder. In one embodiment, the second position is different than the first position.
The invention further provides a software program for determining whether knock is present within a motorcycle engine. The software program detects knock by repeatedly sampling a position signal indicative of a position of a first piston in a first cylinder, generating a first spark signal resulting in a first spark being generated in the first cylinder when the piston is in a first position, sampling a knock intensity portion of an ion signal, providing a threshold value, comparing the sample with the threshold value to determine if knock is present within the first cylinder, and generating a second spark signal resulting in a second spark being generated in the first combustion chamber when the piston is in a second position and in response to knock being present in the first cylinder.
In addition to determining if knock is present within the motorcycle, the ion signal may be further analyzed to determine if one of the cylinders did not produce combustion in response to a spark-inducing signal. That is, when the microprocessor generates a spark-inducing signal for one of the cylinders, ideally, the respective spark plug generates a spark in the spark gap and combustion results. During combustion, gasses ionize thereby generating an ion current. If low or no ion current is produced, then combustion did not properly occur. This might occur if a spark plug is malfunctioning, a spark plug cable is unhooked, an error is occurring within the fuel system, etc. Such events are generally referred to as no-combustion events, even though combustion of a small amount of fuel in the cylinder may in fact have occurred. Therefore, the ion signal may be further analyzed to determine if a spark-inducing signal resulted in a spark event.
Accordingly, in another embodiment, the invention further provides a motorcycle including a frame, front and rear wheels coupled to the frame for rotation with respect to the frame, and a two-cylinder engine. The engine includes a housing, first and second cylinders having first and second combustion chambers, respectively, and first and second pistons mounted for reciprocal movement in the first and second chambers, respectively. The motorcycle further includes a spark generating circuit including a spark plug having a spark gap exposed to the first combustion chamber, an ion sensing circuit including the spark plug and being operable to generate an ion signal indicative of an ion current generated across the spark gap, and an analysis module coupled to the ion signal circuit. The analysis module is operable to receive the ion signal and to analyze the ion signal to determine whether a no-combustion event occurs in the first cylinder.
The invention also provides a method of determining whether a no-combustion event occurred in a two-cylinder engine of a motorcycle. The method includes the acts of providing a motorcycle, applying a spark-inducing signal to the spark generating circuit of the motorcycle, obtaining an ion signal indicative of an ion current across a first spark plug gap of the spark generating circuit; and analyzing the ion signal to determine if a no-combustion event resulted when applying the spark-inducing signal to the spark generating circuit.
The ion signal may be further analyzed to determine whether an intermittent connection may be present in the spark generating circuit. The intermittent connection results in a non-continuous current path and produces additional noise in the knock signal. For example, the intermittent connection may be a loose spark plug cable or a loose spark plug.
Accordingly, in yet another embodiment, the invention provides a vehicle (e.g., a motorcycle) including a frame, at least two wheels coupled to the frame for rotation with respect to the frame, and an engine. The engine includes a housing, a first cylinder having a first combustion chamber and a first piston reciprocating in the first chamber. The vehicle further includes a spark generating circuit including a spark plug and being operable to generate an ion signal indicative of an ion current generated across a spark gap, and an analysis module coupled to the ion signal circuit to determine if the spark generating circuit has an intermittent connection.
The invention also provides a method of determining whether a spark generating circuit of a vehicle has an intermittent connection. The method includes providing a vehicle having an engine, generating a spark in a combustion chamber of the engine with a first spark plug, obtaining an ion signal indicative of an ion current across the spark plug gap, and analyzing the ion signal to determine if the spark generating circuit has an intermittent connection.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.